The CEO of Target is resigning.  

It was announced early this morning that Target's Chief Executive and Chairman Gregg Steinhafel is leaving after a massive security breach rocked the company last December.  

Steinhafel spent 35 years working for the retailer, the last six as CEO.  

Target's Chief Financial Officer John Mulligan will take over as interim president.  

Target's cyber attack late last year resulted in the theft of tens of millions of credit card numbers.